Heat-treatment of n-alkyl polyamides



Patented Feb. 23, 1954 f' Glaims.

ll'his Vinvention .relates .to elastic .sym .theicstructures such Las.,filamentsfiiiers, yarns., threads -et0,., :andimore particularly to ..a novel method for heat-treating filamentaizy-.stnuritures comprised of .certain .Nfallyil substituted r,poly- .amides .Conolyamdes tformed from yarious .mixtures .(withinlimits .hereinafter `defined) of .salts of .a Straight echain .dihasic caihoxylic .aliphatic acid .containing ...atleast six-,carhon atoms Vinthe endian. unsuhstituted aliphatic diamine containing .atleastnve carbon .atoms Tin .the vchain .and a monoand/or a d- N-alkyl substitutedfali- )Uliano-secondary .diamine ,containing atleast ive canhoniatoms in the chain, .canbe .readily spun vinto .ilamentsand yarns having in. .adition'to high"tenacityghighheatstabilty,.andhiehivaterinsensitivity'., aiconsiderableideeree.otstretchand an .elastic recoyeiiycomparable .to .vulcanized rnbber gives .them .fa Lplace yif .considerable .importance in theleld .of 'textiles rand.the.`1ike.

TheseniehlyelasticLNealkyLsuostitutedicopolyamides Wnenormed ,intozyarnby .-theinelt-.spinning fprocess :commonly .used .in .the .nylon .art are drawn or stretched by alhotor cold-.drawing .process np fto .509% .to .improve 'both 'the tenacityand f recovery properties. .This .may lbe followed, 'if .Idesired, .by a. elaxationsstep which gives ailowernet .draw ratio. Chis .drawing operation, leilen after relaxationidoes not .stabilize theyarnetotskirinkaee onder boil-,01T .conditions or, indeed, `under conditions' less than those .obseriied .at .the-.boiL .isinnsatisiactory since the nsefnlnessof .knit v'or `vi/oiien fabrics .containnesuch .a yarn .would Lloe seriously .reduced tor many textile purposes if under normal .conditions ,oi'its .use .or .vi/.ashingfi-t were toslirink 2'5-50j%,.

Infthe past when suchen .unstable nature has "been rnote'cl 'in yarns made 'from various polymeric materials, asoiution"has"been"to Theatset the V'yarn v`or lfabric, "in "aisingle "stage, und-er critical-temperature and tension conditions :so `that a stable conligura-tion results, "which 'configuration is normaliy resistant-toshririkage during v"'riisiring loperations vor .under *washing and ironing conditions of hthe "fina-l garment. it iwas found, however, vtheft whenk such 'a :heat-setting process in theyioirrity 'of 91E-"100 was tried upon cakes of N-aik-yl *(eg., N-iisohutyl'i'fsnbstituted lccmolya-mide yarns, 'the yarn 'properties from insidefto outside Iof lthe cake were not-miifor-m. The yarn inthe outerisectionsfofthe cake nomi A*tenacity iower'ithan'that n'theinfterior `portion ofthe cake, andinlfactpin some -casesithe tenacity of fthe l-outer y'yarn was only ihalf MAthat of 4the 'inner yarn. lliieffreason *for this nonuniform-ity was atirsttnougintftofbe caused "by non-uniform lheat tnans'fer'ithroughf'the cake. Thishoweverfproved to erroneous when it was "found "that Vevenv single vstrandsmf yarn :so heat-treated Thad Atenacity considerably l"inferior toiiatffofthe start-ingvma'teria. it had l2 .neen .eaiclliermoted that "heat-setting .at .any item- Derature nelow thislaneegave yarns .less stable and of 'heherishrinkage under'boil-.ogt seemed -Q'Jovillus that anew Iprocess .of Jheatfsett'ing 4Woill have tone snowed.

AllObject .of .this invention ithereforeis, .with- .ont damaging .the yarn properties, .5to tuni'tornolyiheat-set .the highly entensiilefhigliiy elastic lamentary .structures forme-.d .from ,poiyamdes comprising Loi-.alkyl .substituted .polyaniides.

y,Another Objectis to provide amethold .'for heattreating .laments Ioeis. yarns, threads ,andlike .stmotnnes of ycQpolyaniiies of ,.sebacic aciil ywith liexametliylenediamine .andvwth mono- `and/.or IiiNeisoloutylhexarnethylenediamine, whereby-.to uniiormly heat-.set saidistrnctures and effectively reduce the shrinkage "thereof under jboilfoliconditions.

lTiloe aboveancl other..ologiects.willmiore Y.clearly .afpllear-nereinaiten These .objects Pare accomnlishedbythisfinvention, which, biieiiystated, comprises subjecting oriented ,.llamentsyarns, .et,c. prepared'romilq- .alkyl sustitutei .copolyaniidesiwherein the .alkyl gronpiw contains. at .least two .carbon atoms, to

,a itwofstaee lheat treatment. l'h'is `.hea'tetreatment .consists of an initial exposure .of Lthe .yarn alt substantially -constant length .to a .suitable .inert heating meciium .sucnas 'cheated water `or air Kat liieih...nelative hum'ii'ty A.untilithe yarn .iis `heated to a 'temperature .0I from EDP-89 JCM. toli lowedby asecond .exposure-to .tl1e.meiiium.unti1 ingatraight 'chain vof ,atleast 'five carbon a'tDmSy vseparai-:ing.tlieamine groups and wherein tithe allyr'group "contains at least -two carbon atoms, with vdiloa'sic. aliphatic carboxylic acid :containing la'."s'trfftight chain of atleast 'six carbon "atoms, inthe proportions mof `:aboutonemol of .combined iiiamines toune-mol Mof' "clibasic acid.

"In a'll V"casesI in iforrning `the reaction product from diamine 'and' Ydibasic: acid, 'theamine componentsfmust 1loe a'fmixture of unsubstitutedzdif:

diamine. V"".ihns'tli'e -polyanfniole made onlylfrolrnf. Nsobdtyhexanretnylene *diamine vand 1 seloacic f acidi-snot an elastic yarn although 'it contains n N-alkyl substituted polyamides.

3 exactly 50% N-alkyl substitution in the diamine. Also, a polymer produced by reacting the dibasic acid with a mixture of N,N'diisobutylhexamethylene diamine and N-monoisobutylhexamethylene diamine will not result in the production of an elastic yarn. The accompanying drawing illustrates a triangular graph based on the use of mixtures of N,Ndiand N-monoisobutylhexamethylene and unsubstituted hexamethylene diamine expressed in mol per cent of each amine in the mixture, the mol per cent of each amine increasing from at the base to 100% at the apex which bears the name of the particular amine. The area ABCDy shown as representing an irregular section of the diagram, defines the area which, for practical purposes, includes the mixtures of diamines on a mol per cent basis which may be used as the amine reactant for producing the polymers and products of this invention. It will be understood that while the area may be shifted somewhat when other diamines and when other dibasic acids are used, the diagram, for practical purposes, represents the proportions of all of the N,Ndi and N-mono-substituted diamines and the unsubsti- 'tuted diamine which may be used. Generally speaking, the diamine mixtures will vary from '75-0-25 to 45-0-55 to 0-55-45 to 0-90-10 within the limits of said area, these numbers representing the mol per cent successively of the di-monoand unsubstituted amines. Thus, 40-20-40 repres'ents a 50% substitution wherein 40% is the ldiand the mono-substituted diamine and is unsubstituted diamine, the degree of substitution, e. g., representing the mol per cent of the theoretical maximum substitution possible. -Since the limits are based on mol per cent, the specific constitution and molecular weight of the amines will not cause any great change in the limits of the field covered by the invention. Likewise, the diagram may be applied in general regardless of the dibasic acid used so long as the dibasic acid contains at least six carbon atoms in a straight chain.

N,N-dialkyl and N-alkyl substituted diamines which may be used in place of those speciiically mentioned above are N,Ndilauryl and N-laurylhexamethylene diamine, etc. and in place of hexamethylene diamine, there may be used decamethylene diamine, et seq. As is so common in s! homologous series, the rst member of the series is abnormal. Thus, in the present case, the use of methyl-substituted diamine, whether dior monin combination with unsubstituted diamine will not yield an elastic yarn. From N-ethyl substitution up, within the conditions described herein, the yarns will be elastic. Thus, a polyamide from N-methyl-substituted hexamethylene diammonium sebacate (-0-40 amine mixture used) elongated only about 25% in the elastic recovery test, whereas the corresponding N-ethyl substituted polyamide had an elongation of more than 100% under similar testing conditions. X-ray diagrams also show the N-methyl-substituted polyamide to be different from other It is not necessary that the N-substitution be completely alithe same for both the diand mono-substituted amines anda different number of carbon atoms may comprise the diierent amines in the mixture, e. g., N -alkyl substituted hexamethylene diamines may be admixed with unsubstituted decamethylene diamine, etc.

Likewise, more than one dibasic acid may be used in the mixture of polyamide-forming reactants to produce different types of interpolyamides. The dibasic acid, however, should contain at least six carbon atoms in the straight chain. `Sebacic acid is illustrative. Alternative representative acids include azelaic, pimelic, adipic, suberic and bis-i-carboxybutyl sulfide.

1 Acids containing an even number of carbon atoms in the chain are preferred from the viewpoint of melting point.

It will be understood that the area ABCD may shift somewhat depending on specific factors, including the particular diamine or dibasic acid, the presence or absence of carbon substitution in either, the particular alkyl substituent and the use of interpolyamides containing two or more or the diamines or dibasic acids or both. In general, the area ABCD will cover the useful range.

It is to be understood too, that these illustrative examples, reversing as they do previously conceived opinions, will make it possible for experts to synthesize related elastomers not specifically discussed and this invention contemplates such related polyamides. For example, one can have interpolymers of different polyamides and phatic; thus, in addition to the strictly alkyl subless substitution will be required as the unsubstituted interpolymer tends to have elastic properties itself. Thus, an interpolyamide made from pexamethylene diamine and adipic acid, hexamethylene diamine and sebacic acid, and caprolactam in the proportions of 40-30-30 described in 'i Brubaker U. S. Patent No. 2,285,009 is already soluble and of a loW degree of elasticity. When in such an interpolyamide, the sebacic acid is reacted with a mixture of N,Ndiisobutylhexa methylene diamine and N-isobutylhexamethylene diamine to produce a final interpolyamide having 21% of its nitrogen substituted, the polymer is substantially more rubbery than that of the simple system previously described. The' poly-'- mer has a low melting point and a high water sensitivity, probably due to its complexity, but it can be quite interesting for certain uses.

The copolyamides hereinabove deiined, may be prepared from a mixture of separately prepared diamine-dibasic acid salts as generally described e. g., in Carothers U. S. Patents Nos. 2,071,250, 2,071,251, 2,071,253 and 2,130,948.

These copolyamides, as described previously, have good recovery from high extensions. Thus an undrawn unstretched yarn possesses an elongation in excess of l00% and elastic recovery in excess of such undrawn yarns, however, remain tacky for a considerable period of time immediately after spinning. The yarn gradually becomes non-tacky. Such reduction in tackiness is promoted, however, by imparting a considerable degree of stretch to the yarn after it has been extruded from the spinneret. Thus, if a yarn made by this invention is stretched 500% by passing it between stretching rollers,it loses tack, may be easily handled and may be directly wound thereafter on a bobbin and may subsequently be unwound therefrom. In connection with the matter of tackiness, it is preferred that immediately after the yarns have been solidified and anti-tack agent (e. g., talc or other Tamidst-iieammiratittzifrfonceimittendrins :of elasticity) required to extend the yarn a given percentage also increases. Thus, the stretching and Winding conditions are preferably so chosen in accordance with Well understood principlesmstto yobtain the optimum relationship of yarntprope'rltiesfor a particular use.

The temperature of spinningavariesidepending upon the spinning viscosity ofv the polymer, that temperature being used at which the viscosity? df the polymer is suitable for spinning :under the conditions used. Generally spelingfthetemperature of spinning varies from G-285 C. Meltspinning is preferred, although solvent-spinning may `be used if desired. .l

The annealing temperature of the .processiof this invention is between 60 ande80 Ciwhenta liquid bath medium is used. .Thefstaitingtemperature, of course, may be lower'as longea'si the yarn being treated does not passthroughiheea'nhealing range faster than a.minimum.-.-heatir1er` l.tltteinpereture;may be tbieratdlbecausefithe '-tflhel ffollowingtspec'ic: representative examples .-untheriillustrateethaprinciples-.Vandmpractica. of thisf.' invention '20 pressurefforfhalfisanhour. A zvacu-um `gis-:..then

tgradually applied iwith agitationuntil a pres- `.sui1e...of .L1-25 amm. -LI-Ig...is...reached Agitation is continued Builder thetreducedfpressureuntil the desired degree of :polymerization is 'reahed, A,as

indicatedby the melt viscosity. Relative viscosity at'this point' is'"'3'5. "The molten polymer' is then melt-spun by the conventional yprocess througma spinneret into a cooling atmosphere where slidication of the laments occurs.

After this solidication of the yarnr occurs'an'd before Wind-'upjztalc `.is applied .toiprev'ent the stikingioifthe individual'laments. 'Li-Theyyarmas Spun has'15.,-.1ilaments and a 4301totalz denier. ..fIliis .yarn mis thendrawn by ,conventional cold-drawing process.- (.U...S..25290.2,32-1Babcock) about 200%@so thatifthe'riinal denierfis...in.the Yiicinityzof"200. 'Ilhis yarnhas atenacity of .85 gram perdenier` g. pid.) an'd abreak 'elongation of 300%. When a sample. of.jth is.-ldrawn 4@ ,yarn .is boilediofftior aperiod of..10. .mnutes .it is .observedtolshrink 40 5%, .[Sereral l-.samblesbfgiihis idraW-nhut .not,boiledoiyarm are. then ..giyen an .annealing.treatinen'tt as..indicated.-below,.,followed by a finaliheat-fsetting fpperationwint-.Watereat 90 C.100 C. to give a residual shrinkageqof the order of: 2e3 .The'ifarnifisxon :cohesrduring -fthe :annealing -reatmenteandlthenheatesettingstreatfrnent. Sltiismhusheld ateiixedilengthxandiis. not treeitofsh'rink. :.flo'tdemonstratetheimprovement f) ofi this inventiomtheresisfshowrr `,in'flable Iii-the fdiierences'ironrlthelinside -tofthefoutsidetfithe yarn-package Whei1'1-the-yarrrpaekage isi-exposed l*to* the final "heat-estting temperature withoutfaa 5 'prior annealing"treatment'as"*compare'd-torthe uniformity. 'o'fxthef producty `wit/.herrthis processs used. 'No"data are shownf-or yarn'fromltheginside. of .the.' yarn pabkagepinjthe -case .oi-.then annealed. yarn,..sincethere is. ndsubstantial .d'ier- .fsu ence Iromtheoutsideyamn.

t i,Elasticfrecowery,funeXercise iThe yarn isstretchedg i0C.%f1and -;heldior.60 ecp., then releesedflor. BQ snc.

.mandmeasunedagaiin I #Percenttrecvery- As an alternative procdure the yarn either on a cone or bobbin or as single ends may be entered into a liquid bath maintained in the vicinity of 50-80 C. and the temperature raised as rapidly as desired up (minimum time of the order of 30 seconds for yarn on cones, spools, bobbins, and the like or about 3 seconds for yarn as single ends) to the final heat-setting temperature in the vicinity of 100 C. in the case of Table Il and at least one member of the group consisting of an N-alkyl substituted aliphatic diamine and an N,N'dialkyl substituted aliphatic diamine each containing a straight chain of at least iive carbon atoms and each alkyl group containing at least two carbon atoms, and (3) a straight chain aliphatic dibasic carboxylic acid containing at least six carbon atoms in the chain, the relative proportions of said unsubstituted diamine, said alkyl 90 C. in the case oi' Table III. The following lo substituted diamines, and said acid being such tables show examples of a yarn so treated, the as to come within the area ABCD of Fig. 1 of yarn being the same as that described in Table the accompanying drawing, in a medium from I. The properties of the yarn at various locathe group consisting of water, and air at a high tions in the package are determined to show the relative humidity to a temperature of from 60 uniformity throughout the cake. 15 to 80 C., at substantially constant length for Table Il I ron @aecl i- Stivs' at Break e011 on Example oiloycadriiin First Yam Heat cent 'nexer- Tenacty llqii- Elqn' shrinkage,

package Treatment cised/Exer- (g' D gation Pgfg". Percent cised (g. p.d.)

oui-sies..- so.wsner=- gas/08.2 0.75 .ooi 312 4 buddha... 50 C waterz--. 0in/98.3 0. 75 .090 302 3 [nside- 50 G. water 2--. 94.3/98.5 0. 77 .093 322 3 l Same as Table I. 2 Initial water temperature.

Table III L mi erficl ifs Stisrsys at Break Bonos Example orriiin Firrglemt cent Unexev rrgcy Elorliltfig Stlirinkage,

package csclglier- (gg-aging.) Percent ercent Outside--. 50 C. water 2... 93.01082 0. 88 .084 289 3 {Midd1e 50 dwazen-.- gaa/ess 0.90 .085 200 s inseam-. 50 o watsr 1--. @ao/08.2 0.0i .089 :soi a l Same as Table I. 2 Initial water temperature.

As many widely different embodiments may be at least 3 seconds and thereafter heating said made without departing from the spirit and scope 40 yarn at substantially constant length and at a of this invention, it is to be understood that said temperature of from 90 to 100 C., for from about invention is not to be restricted in any Way ex- 5 minutes to about one hour. cept as set forth in the appended claims. 3. The process of claim 2 wherein the unsub- 1 daim; 45 stituted diamine is examethylene diamine, the N 1. The process which comprises heating yarns alkyl substituted diamine is N-isobutylhexaof oriented filaments of a copolyamide produced methylene diamine, the N,Ndialkyl substituted by reacting (l) at least one unsubstituted alidiamine is N,N-diisobutylhexamethylene di- .phatic diamine containing a straight chain of at amine, and the acid is sebacic acid. least iive carbon atoms separating the amine 4. The process which comprises heating a yarn groups, (2) at least one member oi the group of oriented filaments of a copolyamide produced consisting of N-alkyl substituted aliphatic diaby reacting (i) an u nsubstituted aliphatic dimines and N,N'dialkyl substituted aliphatic amine containing a straight chain of at least diamines each containing a straight chain of at five carbon atoms separating the amine. groups least five carbon atoms separating the amine and each alkyl group containing at least two cargroups and each alkyl group containing at least bon atoms, (2) at least one member of the group two carbon atoms, and (3) at least one straight consisting of an N-alkyl substituted aliphatic dichain aliphatic dibasic carboxylic acid containamine and an NN'dialkyl substituted aliphatic ing at least six carbon atoms in the chain, the diamine each containing a straight chain of at relative proportions of said unsubstituted dialeast iive carbon atoms, and (3) a straight chain mines, alkyl substituted diamines, and acids bealiphatic dibasic carboxylic acid containing at ing such as to come within the area ABCD of least six carbon atoms in the chain, the relative Fig. 1 of the accompanying drawing, in a medium proportions of said unsubstituted diamine, said from the group consisting of Water, and air at a alkyl substituted diamines, and said acid being high relative humidity, to a temperature of from Sugh as 1-,0 come within the area ABCD of Fig 1 60 to 80 C., at substantially constant length for of the acompanymg drawing in a medium from at least 3 seconds and thereafter heating said the group consisting or water, and air at a high yarn at substantially constant length and at a emtve humidity While maintaining Said ma.. temperature 0f from 90 t0 100 C, OI m about ments at substantially constant length, the said 5 minutes t0 abOlli One 1101112 70 heating procedure proceeding gradually from an 2. The process which comprises heating yarns of oriented filaments of a copolyamide produced by reacting (l) an unsubstituted aliphatic diamine containing a straight chain of at least ve carbon atoms separating the amine groups, (2)

9 which said yarn is held for a period of at least about ve minutes.

5. The process of claim 4 wherein the unsubstituted diamine is hexamethylene diamine, the N-alkyi substituted diamine is N-isobutylhexamethylene diamine, the N,Ndialky1 substituted diamine is N,N-diisobutylhexamethylene diamine, and the acid is sebacic acid.

OLAF A. BREDESON.

References Cited in the ille of this patent UNITED STATES PATENTS Number Name Date Rugeley June 6, 1939 Miles Jan. 12, 1943 Hanson Oct. 31, 1944 Irons Aug. 8, 1950 

1. THE PROCESS WHICH COMPRISES HEATING YARNS OF ORIENTED FILAMENTS OF A COPOLYAMIDE PRODUCED BY REACTING (1) AT LEAST ONE UNSUBSTITUTED ALIPHATIC DIAMINE CONTAINING A STRAIGHT CHAIN OF AT LEAST FIVE CARBON ATOMS SEPARATING THE AMINE GROUPS, (2) AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF N-ALKYL SUBSTITUTED ALIPHATIC DIAMINES AND N,N''-DIALKYL SUBSTITUTED ALIPHATIC DIAMINES EACH CONTAINING A STRAIGHT CHAIN OF AT LEAST FIVE CARBON ATOMS SEPARATING THE AMINE GROUPS AND EACH ALKYL GROUP CONTAINING AT LEAST TWO CARBON ATOMS, AND (3) AT LEAST ONE STRAIGHT CHAIN ALIPHATIC DIBASIC CARBOXYLIC ACID CONTAINING AT LEAST SIX CARBON ATOMS IN THE CHAIN, THE RELATIVE PROPORTIONS OF SAID UNSUBSTITUTED DIAMINES, ALKYL SUBSTITUTED DIAMINES, AND ACIDS BEING SUCH AS TO COME WITHIN THE AREA ABCD OF FIG. 1 OF THE ACCOMPANYING DRAWING, IN A MEDIUM 